1) Field of the Invention
The present invention relates generally to the field of illumination and, more particularly, the invention relates to a solid state lighting source such as a light-emitting diode (LED) device that provides prolonged emergency lighting in response to a power loss event.
2) Description of Related Art
Periodically, homes, offices, public buildings, hospitals, industrial manufacturing facilities and the like, experience emergency situations which cause power failures leaving these buildings entirely without light. Such power failures may result from electrical short circuits, brownouts, fire, accidents, natural disasters (i.e., floods, hurricanes, tornados, etc.) or a planned shutdown of electricity within a facility or dwelling. Should these facilities remain without power, especially in the critical areas of these facilities (e.g., intensive care units of hospitals, exit hallways and stairwells generally, and the like) the public safety is placed at risk. Accordingly, local, state and federal authorities have required that emergency lighting systems be installed in all critical areas of public buildings.
Conventional stand-alone emergency lighting systems consist of incandescent, fluorescent or halogen lamps powered by NiCad, NiMh, Alkaline, or sealed lead battery modules. Such units are generally able to provide between 1 and 3 hours of effective emergency lighting. Unfortunately, however, most emergency-generated power outages last much longer than three hours. Further, the need for effective lighting may not be realized until the disaster has abated. For example, after a fire or earthquake rescue crews may need to search buildings or other dwellings for injured occupants. In such cases, rescue crews are currently left to perform their search and rescue without the aid of emergency light.
Accordingly, a need exists to provide a device for automatic, high-level illumination that is capable of immediate activation in response to a disruption of power. In such emergency situations, it is desirable for the illuminating device to be efficiently powered by a single battery pack or the like, such that the device is capable of constant high-level illumination lasting for several days or even weeks. Further, the illuminating device should be easily configured to adapt to existing fluorescent, incandescent or halogen light fixtures.